Design and sensitivity analysis of a reduced-order rotor flux optimal observer for induction motor control

This paper aims to give simple and effective design criteria of rotor flux reduced-order observers for motion control systems with induction motors. While the observer is optimized for rotor and stator resistance variations, a sensitivity analysis is carried out in the presence of variations of all the motor parameters by means of either transfer function from true to observed rotor flux or simulation in a MATLAB-SIMULINK environment, assuming the voltages supplying the motor to be different from those supplying the observer. The sensitivity analysis makes it possible to establish design criteria for the observer in question. The behaviour of the proposed reduced order observer is compared with current model and voltage model observers. Experimental results are also given, with the dual aim of confirming the validity of this design method and showing that the observer can be implemented on microprocessor-based devices.